Where has my CYA gone?

[Guest]

Just did AA treatment. Before AA, CYA is 40.
After AA, CYA < 30.
What happened to CYA?
Here is what I added during AA treatment.
Let CF to 0, and added Poly 60 for 8oz/10k gal
Added 2 lb AA, and some MA to lower pH below 7.2.
Added 2 bottles of Pink Stuff
After 24 hours, although the improvement is not significant (maybe the stains are not so heavy even before AA),
I added 4lb of baking soda to increase TA from 70 to 80~90.
Added some MA to let pH stay < 7.2. (but increase quickly back to 7.4 after a couple of hours)
Added about 1 gal 8.25% bleach to bring up FC back to 3ppm.

The problem is the CYA is less than 30 now

What has happened? Should I wait a couple of day to test CYA again before adding stabilizer?
If I have to add stabilizer, can I use some leftover Trichlor pucks according to PoolCalculator to increase CYA?

 

[JasonLion]

It is possible for CYA to disappear any time FC is zero, though having it happen any time other than over the winter is quite unusual. CYA can be broken down by certain kinds of soil bacteria, which are easily killed by chlorine.

It is also possible that this is a testing error. The CYA test is not all that precise to begin with and results vary somewhat in different lighting conditions.

Yes, using trichlor is a valid way to raise CYA, but keep in mind that it is fairly slow.

 

[Guest]

It is possible for CYA to disappear any time FC is zero, though having it happen any time other than over the winter is quite unusual. CYA can be broken down by certain kinds of soil bacteria, which are easily killed by chlorine.

It is also possible that this is a testing error. The CYA test is not all that precise to begin with and results vary somewhat in different lighting conditions.

Yes, using trichlor is a valid way to raise CYA, but keep in mind that it is fairly slow.

Thank you very much for your answer!
I tested it twice today, even indoor light, I can still see the dot at 30 CYA mark
Last week, my CYA testing was 40, and 2 pool stores also read my CYA at 40.
So, some unusual things must have happened...
I regretted to do the AA treatment

As for Trichlor, ThePoolCalculator shows 8oz can increase CYA by 2.2 (15k gal pool).
So, after I used 5 pucks (increase CYA by 11), how long should I wait to test CYA again?

 

[JohnN]

I believe with tablets CYA shows up basically right after they dissolve.

 

[Richard320]

As for Trichlor, ThePoolCalculator shows 8oz can increase CYA by 2.2 (15k gal pool).
So, after I used 5 pucks (increase CYA by 11), how long should I wait to test CYA again?

That stuff should show up pretty quick. I'd say as soon as the pucks are dissolved you can retest.

 

[Guest]

As for Trichlor, ThePoolCalculator shows 8oz can increase CYA by 2.2 (15k gal pool).
So, after I used 5 pucks (increase CYA by 11), how long should I wait to test CYA again?

That stuff should show up pretty quick. I'd say as soon as the pucks are dissolved you can retest.

Sounds great.
It seems that Trichlor is a better way to raise CYA than pure stabilizer

 

[Richard320]

As for Trichlor, ThePoolCalculator shows 8oz can increase CYA by 2.2 (15k gal pool).
So, after I used 5 pucks (increase CYA by 11), how long should I wait to test CYA again?

That stuff should show up pretty quick. I'd say as soon as the pucks are dissolved you can retest.

Sounds great.
It seems that Trichlor is a better way to raise CYA than pure stabilizer

It's good to top it off, but it takes too long when you're needing a lot. By the time you dissolve enough pucks to get CYA up to, say, 30, the pool will be green because the chlorine the pucks released would be gone to sunlight about as fast as it left the floater!

 

[linen]

It seems that Trichlor is a better way to raise CYA than pure stabilizer

Generally not.

If you need to raise your cya just a little, then trichlor can help, but it also lowers ph and TA.

If you need to raise cya a lot, then it is a bad choice since you can only add a little at a time since it also adds chlorine, lowers ph, and lowers TA.

 

[Guest]

Generally not.

If you need to raise your cya just a little, then trichlor can help, but it also lowers ph and TA.

If you need to raise cya a lot, then it is a bad choice since you can only add a little at a time since it also adds chlorine, lowers ph, and lowers TA.

I see. But using pucks is really convenient, just put them in the chlorinator and no need to add bleach either.
My pH raises 0.1 daily. So, I am constantly adding MA, and bring TA back after some time...